1. Field of the Invention
The present invention relates generally to storm drains, and in particular to a prefabricated inlet adapted for cast-in-place or precast storm drain collection boxes.
2. Description of the Related Art
Precipitation runoff is commonly collected and handled with storm drainage or storm sewer systems. Paved structures, such as roadways and parking lots, tend to generate relatively large volumes of runoff during precipitation events. They are commonly designed to gravity-drain relatively quickly for safety and to prevent flooding.
Roadways, parking lots and similar structures are commonly provided with storm drain collection boxes, which are installed below grade and collect runoff for discharge to underground storm sewer systems. Poured-in-place and precast concrete are commonly used for constructing storm drain collection boxes. The inlets for such collection boxes are typically located at the structures lowest elevations and are designed for receiving relatively large flow rates. Storm drain inlets have previously been made of poured concrete, which can be cast when the collection boxes are constructed. U.S. Pat. No. 4,844,183, which is assigned to me, shows a reusable form for storm sewer collection box inlets. However, forming and casting concrete inlets tended to be relatively labor-intensive.
Alternatively, relatively strong storm drain inlets can be efficiently prefabricated from steel plates using conventional steel manufacturing equipment and procedures. Steel provides considerable strength and can be galvanized or otherwise finished for weather-resistance.
Previous storm drain inlets were often rigidly attached to adjacent curbs by extending reinforcing steel between the collection boxes and the adjacent curb structures. Such rigid connections led to damage from shear and related forces. Storm drain inlets should preferably accommodate movement within certain design parameters relative to surrounding structures and terrain, including movement associated with settling and freeze-thaw cycles. Moreover, they should be adaptable to prefabrication and facilitate efficient and cost-effective construction. Scalability can also be an important consideration in storm drain inlet design because collection boxes of various widths can this be accommodated with a basic inlet design. Still further, inlets should preferably facilitate water flow into the collection boxes with minimal obstructions.
Heretofore there has not been available a storm drain inlet with the advantages and features of the present invention.